Dramix® 4D Reinforces India’s First Fiber-Only Precast Metro Tunnel

Delhi Metro’s Package DC 05 introduced India’s first precast tunnel lining designed without rebar, using Dramix® 4D steel fibers. Covering 350 segmental rings between Nabi Karim and Sardar Bazar stations, this milestone showcased faster, safer, and more sustainable metro construction.

The challenge

Traditional rebar in precast segments caused congestion, honeycombing, cracking during demolding, and slow cycle times. The project required a reinforcement solution that improved productivity, reduced CO2 , enhanced durability, and eliminated safety risks of bar handling in factory operations.

The solution

Package DC-05 replaced conventional rebar with Dramix® 4D 80/60 BGP steel fibers in all precast tunnel segments. With C40/50 concrete and fiber dosage optimized via design software, 350 rings were produced in factory-controlled settings. Fibers provided three dimensional reinforcement, superior crack and impact resistance, and durability while eliminating rebar congestion, welding, and placement issues. Productivity improved from 300–500 m²/day to 500–2000 m²/ day, steel usage was cut by over 50%, and carbon footprint dropped by two-thirds (~12 eCO2 /m² to ~4 eCO2 /m²). Local manufacture of Dramix® ensured uninterrupted supply and consistent quality. This pioneering DMRC project set a national benchmark for sustainable, f iber-only precast tunnel lining.

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Dramix® 4D Reinforces India’s First Fiber-Only Precast Metro Tunnel

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